MIGRATIONS OF WATERFOWL 



sight of the water's surface, by which they might perceive velocity as well 

 as wind drift. It is possible that there were ocean swells or waves, although 

 the account does not tell about this; and when still some distance from 

 their destination, the sound of bird voices and surf might aid navigation. 

 Their objective was not a pinpoint of land, but a shoreline several miles 

 broad which, when reached, could be followed to the nesting place. Perhaps 

 these coordinates are not entirely accurate, but they are sufficiently in line 

 to permit a more critical examination of this local travel. The object here 

 is not to oversimplify such movements ; the flight of murres through fog on 

 their home range is indeed a complex performance. But it is not migration. 



In spring the sky is sometimes clear over the Delta Marsh and the gen- 

 eral weather situation ideal for migration, but over the ice-covered lake the 

 blending of moist warm air and cold air brings a heavy fog. At such times I 

 have seen ducks start out in migration, always to turn back upon striking 

 the mist. When fog reigns at Delta, the passage of all species comes to a 

 standstill. On the morning of April 27, 1951, Premier D. L. Campbell, 

 Colonel Arthur Sullivan, and I, driving westward over the prairie from 

 Winnipeg, saw many flocks of blackbirds and great numbers of Flickers 

 flying northwest over the open country toward Lake Manitoba. When I left 

 my companions at Portage la Prairie and drove north toward Delta, the mi- 

 gration was still so strong that I was never beyond sight of traveling birds. 

 On reaching the south edge of the marsh, however, I came suddenly into 

 a heavy fog that reduced visibility to a hundred yards. Near the north edge 

 I saw a Flicker perched on a roadside telephone pole and I stopped to 

 frighten it. At this point the road angled to the northwest and the Flicker 

 launched north into the gray void. Just as it was about to disappear from 

 my sight, it turned west to the road, where it alighted on another pole. The 

 same performance was repeated, but the third time the bird gained sight 

 of the ridge and flew on to the trees. 



At Delta I found Flickers everywhere, perched singly or in clusters in 

 maple and willow. When flushed, a bird moved only fifty or sixty yards to 

 alight again. Many Robins and blackbirds were also sitting quietly in the 

 trees. Peter Ward said that the visibility had been good in the early morn- 

 ing and that there had been no Flickers or other migrants on the ridge at 

 8:30 a.m. A strong passage had reached Delta about 9:00 a.m., but the 

 flight stopped when the heavy fog had closed in soon after. All these birds 

 remained stationary until the fog lifted in the afternoon, whereupon migra- 

 tion was resumed. 



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